1. Field of the Invention
The present invention relates to a file system, and more particularly, to a method of hiding a specified directory with no effect on the compatibility of an existing file system.
2. Description of the Related Art
In general, an operating system (OS) uses a file system in order to manage data on a system, in which the operating system is installed. The file system is a logical structure that should be constructed in order to manage files. For example, in a Microsoft Windows operating system environment, a format command is a process of creating and initializing such a file system. As such, after the file system is generated, a user can store or delete the files.
Various file systems exist depending on the type of various operating systems. Various file systems, such as the File Allocation Table (FAT) file system or New Technology File System (NTFS) in Microsoft Windows operating systems environment, and Unix File System (UFS), Extended 2 (EXT2), Extended 3 (EXT3), Journaled File System (JFS) in operating systems of Unix/Linux exist. These file systems each provide various additional functions, such as data encryption or data compression.
The known file system for storing and managing the files can be generally divided into two areas. One is a data area where actual data of the file is stored, and the other is information area where information pertaining to the file is stored. In the information area, the attribute, rights, name, and position of the file are stored.
In particular, the FAT file system (FAT12, FAT16, or FAT32) uses information of a parent directory in order to access files or directories. During this time, the file system queries a hidden area manager whether the parent directory, or a search directory or file exists in the hidden area. When the directory or file exists in the hidden area, unlike an operation method of a normal FAT file system, information is not read from the physical storage device, and information possessed by the hidden area manager is used.
FIG. 1 is a diagram showing the schematic configuration of a FAT file system 5. The file system 5 has an Master Boot Record (MBR) area 1, a FAT area 2, a directory entry area 3, and a data area 4. Of these, the MBR area 1, the FAT area 2, and the directory entry area 3 are information areas of the file system 5.
The MBR area 1 is a common portion, regardless of an operating system, and is located at the top of a physical storage medium, such as a hard disk. The MBR area 1 includes information on partitions and execution codes related to booting.
One or more files on the FAT file system 5 are read through the following steps. First, a first cluster number is read from the directory entry area 3 through a file name and an extension. Then, data dispersed in the data area is read from positional information in the FAT area 2 through the first cluster number by connecting clusters where specified data is stored.
In contrast, in a process of storing files in the file system, first, information of the files to be stored is stored in the information area. At this time, information of the file size, and first cluster number is stored in the directory entry area 3, and positional information of data is stored in the FAT area 2. Next, actual data of the file is stored in the data area 4. In a file system other then the FAT file system, basically, the files are managed in the information area and the data area.
In recent years, in order to prevent leakage of personal information or important data, security is increasingly demanded in a mobile apparatus or an internal apparatus. However, in a FAT file system that is widely used in such apparatuses, a function of hiding a specified file or folder in a file system level is not provided.
Conventionally, in a FAT file system, the attribute of the file or directory can be set as “hidden”. However, this method merely sets the attribute, and any application can cause the content of a file or a directory having a hidden attribute to be viewed (hidden file view function), and can access the file or directory at any time.
Accordingly, a technique that can keep security from the access of the application by hiding the specified file or directory in the file system level is demanded.